BACKGROUND ART Our earlier patent application W099/15732 described a rail damper in which tuned resonant members are held within a compliant block. This is affixed to a side of the rail, resting in the corner formed by the rail foot and the rail web. Figure 1 shows a damper of this type.

It is necessary to retain the damper in place on the rail. This must be done securely and permanently, as if the damper were to become loose then it could become a hazard to passing rail traffic. Hitherto, this has been achieved by gluing the damper to the rail.

SUMMARY OF THE INVENTION Rail operators would prefer the damper to be attached to the rail in a manner that permits easy and swift removal. Rails must be repaired from time to time, and as rails age they are moved from high traffic locations toward lower traffic locations where less demands with be placed on them. Thus, if the damper were removable, the management of the rail network would become more straightforward.

Rail installers would also prefer a means of attachment for the damper which could be executed more swiftly than a gluing operation. This would allow improvements in efficiency during the installation of the damping devices.

The present invention therefore provides a clip for a rail damper, comprising a hook adapted to attach to the foot of a rail on one side, a first elongate member arranged to extend from the hook beneath the rail foot, a second elongate member extending in a direction transverse to the first, and a retention element adapted to retain a damper on the second side of the rail.

There are preferably two of each of the first and second elongate members. These can extend in divergent directions so as to attach to the damper at spaced locations. This will then provide suitable bracing for the clip so that it can remain in a tensioned state and retain the damper in place. Other methods of bracing the clip could of course be employed.

The clip is preferably formed of a single rod, of a suitably resilient material <BR> <BR> stich as steel, especia"y spring steel. The rod can be in a shape which, from end to end, consists of a retention element a second elongate member, a first elongate member, the hook, a further first elongate member, a further second elongate member, and a further retention element.

The retention element can be a bend in (for example) a clip formed of a rod. A bent end part will be able to engage with the resilient material of the damper, or engage with a recess in the damper, or engage otherwise. Where it engages with a recess, this will provide a useful anti-tamper device.

A clip of this type is easy to attach and can be installed and uninstalled swiftly. An additional advantage is that the hook will, to an extent, retain a damper in place on the one side of the rail. Thus, if the clip retaining this damper fails, the damper will nevertheless be held in place. This may be insufficiently secure to allow proper acoustic coupling between the rail and this damper, but the damper will at least not present a safety hazard.

In such a damper, the two elongate members allow the clip to flex in two different directions, that is vertically and transversely (with respect to the rail).

This allows the damper to be pressed both downwards onto the foot and inwards onto the web. Other designs of clip tested by the applicants pressed the damper into place in one direction only and provided lesser acoustic coupling between the rail and damper.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 shows a perspective view of a rail, damper and clip according to the present invention; Figure 2 shows a side view of a rail, damper and clip according to the present invention; Figure 3 shows a vertical section through a rail, damper and clip according to the present invention; Figure 4 shows a plan view of a rail, damper and clip according to the present invention; Figure 5 shows a perspective view of a rail, damper and clip according to the present invention; Figure 6 shows a side view of a rail, damper and clip according to the present invention, from the opposite side as compared with figure 2; Figure 7 shows a perspective view of the clip according to the present invention; Figure 8 shows a perspective view of a further embodiment; Figure 9 shows a vertical section through the embodiment of figure 8, illustrating the join between the two rods; Figure 10 shows half of the clip of figures 8 and 9 in an unstressed state prior to fitting; Figures 11 and 12 show the half clip of figure 10 after fitting, in perspective and plan views respectively; Figures 13,14 and 15 show arrangements for joining the two half clips ; and Figures 16 and 17 show further embodiments with greater flexibility.

DETAILED DESCRIPTION OF THE EMBODIMENTS Referring to Figure 1, a rail 10 consists of a head 12, a web portion 14 and a foot 16. As explained in our earlier application WO 99/15732, a damper 18,20 can be placed on either side of the rail resting on the foot 16 and against the web 14. The internal construction of this damper is preferably as shown in WO 99/15732, but this invention is applicable to any form of damper which locates against the rail in this way.

A clip 50 is shown in Figure 1 to retain the damper 18 in place. In practice, a corresponding clip would be provided for the damper 20 on the opposite side of the rail, usually at a spaced location relative to the clip 50. This second clip is not shown in the figures, but can be of similar or identical construction.

The clip 50 consists of an elongate bar of spring steel which is bent into a suitable profile. Visible in Figure 1 are the ends 52,54 of the bar which include bent portions which are directed downwardly into the bulk of the elastomeric damper 18. It can then engage with the damper so as to hold it securely.

Recesses can be provided in the damper if desired, but typically the spring force of the clip 50 and the resiliency of the damper material 18 will be sufficient to allow a good engagement. From the engagement portions 52,54, arms 56, 58 extend transversely outwardly of the rail. At a position where it is clear of the rail foot 16, the bar of the clip 50 then bend again to provide vertical spring members 60,62, which extend downwardly at approximately 45° toward each other.

The above parts can also be seen clearly in Figure 2.

In Figure 3, it is apparent that after the downward sprung arms 60,62, the rod material of the clip 50 then bends again to a horizontal spring arm 64, 66 (not visible in Figure 3). This then traverses beneath the rail foot 16, travelling generally horizontally at a slight acute angle to the direction transverse to the rail 10. It emerges on the other side of the foot 16 with an upwardly directed hook 68 which retains the clip on the opposite side of the rail 10, adjacent the damper 20. This hook is formed of a generally U-shape, the curved end of the U being directed toward the damper 20 and the two legs of the U leading to each of the horizontal spring sections 64,66, as shown in Figure 4.

Figure 5 shows a perspective view of the system from the opposite side, from which can be seen the U-profile of the hook 68 leading to the horizontal spring sections 64,66.

Figure 6 shows a side view from the opposite side, showing the slight divergent angle of the horizontal spring member 64 and 66.

Figure 7 shows the complete clip without any intervening items, and it can be seen that the clip is formed on a single elongate section of spring steel rod section formed into the appropriate shape.

In use, the device can be fitted by placing suitable dampers on either side of the rail and, at intervals, removing some ballast to allow access to the underside of the rail foot 16. The device can then be held via the vertical spring section 60,62 and the hook 68 past the rail section. By suitable forward pressure and rearward bending of the vertical spring sections, the hook 68 can be made to engage on the opposite side of the rail. The spring section 60,62 can then be bent accordingly, with suitable resilience in the correct direction being provided by all four spring sections 60, 62,64, 66 to allow the engagement sections 52,54 to be engaged with the upper surface of the damper 18. Once in place, the vertical spring section 60,62 will be in a suitable tensioned state so as to urge the damper 18 downwards onto the foot 16, and the horizontal spring section 64,66 will be in a suitably deformed state so as to urge the damper 18 in towards the web 14 of the rail. Accordingly, good acoustical contact can be maintained between the damper and the rail thereby obtaining the best acoustic performance.

A plurality of such clips can then be provided at intervals along the damper 18. Similar such clips can be provided at intervals along the damper 20.

One advantage of the clip design is that through the use of the protruding hook 68 on the opposite side of the rail, should a clip fail in use then clips holding the damper on the opposite side of the rail in place will provide a measure of retention for the damper. This retention may be insufficient to obtain appropriate acoustic properties, but can in practice retain the damper in place thereby preventing it from becoming a safety hazard.

A first tool can be provided, if desired, to assist in fitting the spring. This tool conforms to the shape of the clip and engages the parts lying underneath the rail in the pre-assembly position. It pivots about the top of the rail and draws the arms out from under the rail. Then, in an upward stroke the arms are drawn inward and over the top of the damper and released by sliding off the tool into the engaged position.

A second tool can also be provided to lift the spring from any engagement slot, enabling it to be removed from the damper, in effect reversing the action of the previous tool and permitting release of the damper.

A further embodiment of a clip according to the present invention is shown in figures 8 and 9. The same rail 10 has a head 12, web 14 and foot 16, and is fitted with dampers 18,20 on either side.

The clip is in two parts 100,102, each in the form of a distorted Z-shape and held together at their centres by one or more circlips 104 as shown in figure 9. One end of each Z-profile engages the upper face of a damper. Each Z- profile thereby engages with both dampers 18,20. A small return 106 at each end assists with this engagement. Between each end, the Z-profile passes diagonally downwards from the top of the damper 18,20 to the foot 16 of the rail 10, then passes beneath the foot 16, crossing the other Z-profile, and rises diagonally upwards on the other side of the rail 10 to the top of the other damper 20,18. Each end of the Z-profiles points in opposite directions relative to the rail 10 and thus the attachments points of each respective Z-profile are spaced along the dampers.

Figure 10 shows one Z-profile in its unstressed state prior to installation.

To aid the process of sliding the clip beneath the rail, the profile is approximately flat in this state. Figure 11 shows the state of the clip after installation, each end having been lifted from its unstressed state shown in dotted, as shown by arrow X. Figure 12 shows the plan view corresponding to figure 11, from which it can be seen that the ends also bend outwardly relative to the rail in the direction of arrows XI.

Through an appropriate adjustment of the dimensions of this embodiment in view of the dimensions of the dampers, this clip can thus be used to retain the dampers firmly in place against the rail foot 16 and web 14.

Figures 13 to 15 shows ways in which the two Z-profiles can be joined under the rail. Figure 13 shows a circlip or a wire crimp 104 joining the Z- profiles 100,102. Figure 14 shows a moulded nylon or other plastics housing 107 joining the Z-profiles 100,102 (shown partly). This will offer protection to the rail from damage. Figure 15 shows an embodiment of this which may in practice be more straightforward to fit, in which an H-profile nylon (or other plastics) carrier 108 has slots 110,112 on either side. The Z-profiles can be pressed into these slots.

The rail clips of either embodiment described above can be provided with sprung sections to relieve stress and increase the available spring deflection.

Figures 15 and 16 show such arrangements. In figure 16, the sprung sections comprise coils 114 at either edge of the rail. In figure 17, the sprung section comprises a coil 116 extending across the entire section of the clip lying beneath the rail 10. In this case, applied as shown to the second embodiment (above), the two Z-profiles can be linked by intimate engagement of the helices of the two coils.

It should be emphasised that the modifications shown in figures 16 and 17 can be applied with equal effect to the embodiment of figures 1 to 7.

Other variations on the above-described embodiments are also possible.

For example, the clip could be composed of two parts that hook around each other on the underside of the rail or to one side. They may variously provide each other with angle guides, so that a protruding part from one of the arms slides into its locked position. This arrangement would enable an automatic machine to install the clips.

In another alternative, the clip could engage with a solid bar running the length of the damper and protruding from the ends thereof. This bar could be one of the resonant masses of the damper, or independent of them. The clip can then be angled forward from the base so that its lateral displacement inwards towards the rail applies a simultaneous lateral and vertical force to the protruding bar.

The clip may need to press onto the damper at a point between the resonant masses. It can therefore engage with a suitable metal or plastic part on the surface of the damper, to distribute the load into the damper. This can be a simple flat section of material with a socket or bore into which the end of the clip can pass. The part can be recessed into the damper, or glued thereon, or simply pressed in place by the clip. In the latter circumstance, a roughened or other high friction surface will assist.

The damper can include a reloaded internal spring pushing against its back face. Thus, when the clip system is in place, this spring can be released to engage against the clip and assist with or provide the engagement force without need to preload the clip in an"open"position.

A rotating cam can be used to apply load between the damper and the clip system. This may be in the form of (for example) a nut with an eccentric hole on the ends of the above clip design, or (indeed) any other design of clip, or it can form part of a separating link between damper and clip, Thus, the present invention provides a clip system that is simple and straightforward to install in a short time, yet can be manufactured cheaply and easily from inexpensive materials.

It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.